Treatment tool for biopsy and tissue collecting method

A treatment tool for biopsy comprising

• a needle tube which is formed with a tubular space and a sharp distal end that is capable of piercing tissue, the needle tube having a first aperture, a second aperture, and at least a first dimple, wherein
• the first aperture is provided in the distal end of the needle tube and communicates with the tubular space,
• the second aperture is provided, in order to collect tissue from an area punctured by the needle tube, in a side surface of the needle tube at more proximal end side than the first aperture, and communicates with the tubular space in the needle tube,
• an end surface of the second aperture comprises both a distal end circular arc portion which is formed in circular arc shape on the distal end side and a proximal end circular arc portion which is formed in circular arc shape on the proximal end side in an axial direction of the needle tube,
• in a cross-section taken in a depth direction of the second aperture so as to include an axis of the needle tube, the distal end circular arc portion comprises a distal end side inclined surface that is inclined so as to be positioned gradually outwards of a radial direction of the needle tube towards the distal end side of the second aperture, and the proximal end circular arc portion comprises a proximal end inclined surface that is inclined so as to be positioned gradually outwards of the radial direction of the needle tube towards the proximal end side of the second aperture,
• blade portions that are used to cut off tissue when the needle tube is moved backwards and forwards in the axial direction of the needle tube are formed on end portions of the distal end side inclined surface and the proximal end inclined surface that are on the second aperture side,
• the second aperture is formed at a different phase position in comparison to a proximal end of the first aperture in the circumferential direction of the needle tube without overlapping the first aperture in the axial direction of the needle tube, and
• the at least first dimple is formed at a phase position including the second aperture in the circumferential direction of the needle tube and at a position between a distal end of the needle tube and the second aperture.